David Bowie ordered everyone working on his comeback album to sign a confidentially agreement to ensure the new material remained a secret.

The rock legend made a triumphant surprise return to the music scene earlier this month (Jan13) by releasing a new track, Where Are We Now? - his first offering in nearly 10 years.

Fans and critics alike were stunned Bowie had managed to keep the recording, and news of his upcoming album The Next Day, out of the press, and now his producer Tony Visconti has revealed the great lengths the icon went to so the project would remain a secret.

Visconti tells Billboard.com, "The members of the band and the engineers, the people who bring us coffee in the studio, everybody who was involved in this had to sign a (non-disclosure agreement) to keep this a secret. The people who played on this album, most of them have worked with David for a long time; to sign an Nda would have been unnecessary for most of them. But we had some new people and a new recording studio we didn't have an old, long-standing relationship with, so we took the precaution. Everyone had to sign it.

"No one objected; they said, 'It's just an absolute joy to be working with David Bowie.' The way we kept it a secret was on an honour system - not that we were worried about being sued or anything like that. It was so cool to be part of this club. That's what it was really about."